From: Scott Marlowe <scott.marlowe@gmail.com>
To: Greg Smith <greg@2ndquadrant.com>
Cc: Jeff <threshar@torgo.978.org>
Cc: david@lang.hm, Hannu Krosing <hannu@2ndquadrant.com>
Cc: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: pgsql-performance@postgresql.org, Albe Laurenz <laurenz.albe@wien.gv.at>
Subject: Re: Linux I/O tuning: CFQ vs. deadline
Date: Wed, 10 Feb 2010 00:11:30 -0700
Message-ID: <dcc563d11002092311od97926fm7e69826995e9ccd0@mail.gmail.com> (raw)
In-Reply-To: <4B725410.5010000@2ndquadrant.com>
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<4B725410.5010000@2ndquadrant.com>
On Tue, Feb 9, 2010 at 11:37 PM, Greg Smith <greg@2ndquadrant.com> wrote:
> Jeff wrote:
>>
>> I'd done some testing a while ago on the schedulers and at the time
>> deadline or noop smashed cfq. Now, it is 100% possible since then that
>> they've made vast improvements to cfq and or the VM to get better or similar
>> performance. I recall a vintage of 2.6 where they severely messed up the
>> VM. Glad I didn't upgrade to that one :)
>>
>> Here's the old post:
>> http://archives.postgresql.org/pgsql-performance/2008-04/msg00155.php
>
> pgiosim doesn't really mix writes into there though, does it? The mixed
> read/write situations are the ones where the scheduler stuff gets messy.
I agree. I think the only way to really test it is by testing it
against the system it's got to run under. I'd love to see someone do
a comparison of early to mid 2.6 kernels (2.6.18 like RHEL5) to very
up to date 2.6 kernels. On fast hardware. What it does on a laptop
isn't that interesting and I don't have a big machine idle to test it
on.
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To: pgsql-performance@postgresql.org
Cc: scott.marlowe@gmail.com, greg@2ndquadrant.com, threshar@torgo.978.org, hannu@2ndquadrant.com, Kevin.Grittner@wicourts.gov, laurenz.albe@wien.gv.at
Subject: Re: Linux I/O tuning: CFQ vs. deadline
In-Reply-To: <dcc563d11002092311od97926fm7e69826995e9ccd0@mail.gmail.com>
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